On known machines for cellophaning packets of cigarettes, a sheet of heat-seal wrapping material is folded onto one wall of the product to superimpose two portions of the sheet of wrapping material by means of a folding device, which gradually releases the sheet of wrapping material once this is folded. When the folding device is fully detached from the wall of the product, a sealing surface of a sealing head is brought into contact with the superimposed portions of the sheet of wrapping material to seal and so stabilize the sheet of wrapping material in the folded configuration.
On known cellophaning machines of the above type, the two portions of the sheet of wrapping material folded one on top of the other against the wall of the product are left substantially free during the time interval between being released by the folding device and being engaged by the sealing surface. During which time, springback of the sheet of wrapping material may cause even a substantial alteration in the configuration of the sheet, thus impairing the quality of the finished wrapping.